Execute Command

[Saurabh Mukadam]

What exactly EXECUTE command/instruction do in flash Magic that makes 89C51Rx2Hxx device restarts with the new application. What is the command sent to 89C51Rx2 when EXECUTE command/instruction is executed ?

[Andy Ayre]

The execute command programs the status byte to zero and then sends a command to ensure the watchdog is turned on. Once the watchdog times out, the device will reset and execute your code.

[Saurabh Mukadam]

Hi Andrew,

Thanks for information. Can you tell me what is the exact command to be sent on serial port to turn on watch dog inside RX2.

[Andy Ayre]

:02000005800178

Rx2/66x rev G and later ONLY. This command only performs the reset.

[Ingo]

Hi Andrew
Looking in the application note AN461_9.

:02000005800178

0001 = read signature byte

[Andy Ayre]

Because of the extra bit that is set - it turns on the watchdog.

No, it isn't possible or necessary to do this via IAP. You simply turn on the watchdog yourself and let it time out. Or use a jump to zero after messing with the interrupts, etc. More info on that method on www.8052.com. I have always found a watchdog reset to be the easiest and most reliable.

[erik malund]

"You simply turn on the watchdog yourself and let it time out.
 Or use a jump to zero after messing with the interrupts, etc.
I have yet to see method 2 working without extensive effort to get all the things right.  So why on earth even try when method 1 is dead easy.

Erik

[Andy Ayre]

I agree. I've never liked method 2. But some people like to punish themselves...

[Saurabh Mukadam]

Thanks Andrew/Erik for information. This will help me alot.